jQuery as new default Javascript library, streaming response support, attr_accessible with roles, prepared statements, easier migrations.

Great blog with daily news and HOWTOs for Ubuntu, Linux and Gnome.

If you have a time given in a different time zone than your local one, parsing will convert it for you:

>> Time.parse('September 2nd, 3pm PST')
=> 2011-09-03 01:00:00 +0200

Note that in pure Ruby you need to require "tzinfo" (Ruby 1.9) or require "time" (Ruby 1.8) for Time.parse to be available.

Let's say you have an Explorer window showing a directory and want a cmd terminal to be opened there.\
While you needed a PowerToy on Windows XP, this is a build-in feature for Windows 7.

Simply press and hold the Shift key and right-click a folder icon or into empty space of an Explorer window.\
Then, choose "Open Command Window Here" from the context menu.

I believe that when WEBrick has trouble bringing up your Rails application, the WEBrick component that is supposed to print you a pretty error message has a bug and sometimes fails with this message:

"undefined method `bytesize' for #<Array>"

Starting the application in Passenger gave me a stacktrace in log/development.log that pointed to the actual problem.

Possible causes discovered by looking at the logs
-----------------------------------------------------...

When writing a piece of reusable code, you sometimes need to have separate code for Rails 2 and Rails 3. You can distinguish between Rails versions like this:

if Rails.version < '3' # mind the quotes
  # Rails 2 code goes here
else
  # Rails 3+ code goes here
end

DeaDBeeF is one of the better music players for Linux.

You can find installation instructions here.

You've been there: A form cannot be submitted, but you don't see a validation error because the field at fault has no corresponding input field on the form. Because this is usually a bug, you insert debug information listing all errors into the form view. And once the bug is fixed, you forget to take out that debug information.

There is a better way. By copying one of the attached initializers into config/initializers, your forms will always render a small box listing all form errors in the bottom right corner of the screen. This box is n...

Just add the parameter :post to the visit method:

visit publish_entry_path, :post

Rails doesn't know which host it is running on. For generating links, it strips the hostname off the request URL, which can lead to errors when you have absolute URLs in your Cucumber tests.

If you really need to use absolute URLs somewhere, say in an email you send, either throw away the host when parsing it (e.g. body.scan(/http:\/\/[^\/]+\/([^\s"<]+)/)) or tell Webrat you're back on your site.

This is a bug in Timecop 0.3.4 or lower. You should upgrade to 0.3.5.

Calling Time#utc, Time#gmt or Time#localtime will not create a converted copy. Instead these methods modify the receiving Time object:

 >> time = Time.now
 => Thu Aug 25 09:52:28 +0200 2011
 >> time.utc
 => Thu Aug 25 07:52:28 UTC 2011
 >> time
 => Thu Aug 25 07:52:28 UTC 2011

This can have unexpected side effects when other code is holding pointers to the Time object you are modifying. To be safe, call these methods on a clone of the Time object. You can clone a Ruby object by using [#dup](http://...

Note that converting from RGB to CMYK will usually degrade your colors because no exact mapping is possible. Anyway, this Stackoverflow post worked for me:

gs -dSAFER -dBATCH -dNOPAUSE -dNOCACHE -sDEVICE=pdfwrite \
-sColorConversionStrategy=CMYK -dProcessColorModel=/DeviceCMYK \
-sOutputFile=output.pdf input.pdf

Use the PDF toolkit:

sudo apt-get install pdftk

To rotate page 1 by 90 degrees clockwise:

pdftk in.pdf cat 1E output out.pdf    # old pdftk
pdftk in.pdf cat 1east output out.pdf # new pdftk

To rotate all pages clockwise:

pdftk in.pdf cat 1-endE output out.pdf    # old pdftk
pdftk in.pdf cat 1-endeast output out.pdf # new pdftk

The E (old pdftk) or east (new pdftk) is meaningful if you want other rotations. From the man page:

The page rotation setting...

Linux provides a fix number of filesystem watches. If you have some greedy daemon (like dropbox) running, chances are it uses all of them, and you cannot use tail -f any more.

To increase the number of watches, put something like
fs.inotify.max_user_watches = 32768
into /etc/sysctl.conf. (default is 8192)

To update the setting right away, run
sudo sysctl -p /etc/sysctl.conf
afterwards.

Retaliation is a Jenkins CI build monitor that automatically coordinates a foam missile counter-attack against the developer who breaks the build. It does this by playing a pre-programmed control sequence to a USB Foam Missile Launcher to target the offending code monkey.

Note that if you plan to downgrade Firefox because your Selenium tests broke after a Firefox upgrade, there is a better way that doesn't involve downgrading. Mozilla has stated that they will no longer provide security patches for any but the most recent versions of Firefox. So running an old Firefox should not be a long-term solution for anything.

If you still want to downgrade your Firefox for other reasons, here is how I downgra...

Note that if you plan to freeze your Firefox versions because your Selenium tests break whenever Firefox updates, there is a better way that lets you keep an up-to-date Firefox. Mozilla has stated that they will no longer provide security patches for any but the most recent versions of Firefox. So running an old Firefox should not be a long-term solution for anything.

If you still wish to disable the auto-update in Firefox, a poste...

Did you return false in a before_validation callback?

Sometimes the Rails helper #distance_of_time_in_words is using too much magic.
When you need a time difference in a specific unit, use this method:
^
def distance_of_time_in(unit, from, to)
diff = to - from

  if 1.respond_to? unit
    distance = diff / 1.send(unit)
    distance.abs.round
  else
    raise ArgumentError, "#{unit.inspect} is not supported as unit"
  end
end

distance_of_time_in(:days, Time.now, 1.year.ago)
=> 365

Remove the .abs if you want the mathematical *differ...

Pdfposter is a Python script that allows to convert large PDFs into a PDF with multiple pages that can be printed and turned into one big poster.

In Ubuntu, you can install it with
sudo apt-get install pdfposter

Scaling to the desired size is a bit cumbersome. If you want to split large.pdf, I suggest you run
pdfposter -vns 0.5 large.pdf larger.poster.pdf
which will tell you into how many pages the file would be split. Then simply tweak the -s value till you get the desired number of pages, and remove the -n to generate the r...

When browsing a repository, pressing "t" allows you to quickly search for file names. Very awesome!

Go here to try it out.

I recently browsed through the ActiveSupport code and found some nice stuff I did not know about:

ActiveSupport::Callbacks

ActiveRecord-like callbacks, if you need callbacks in non ActiveRecord objects

ActiveSupport::MessageEncryptor

encrypt and decrypt ruby objects

[ActiveSupport::MessageVerifier](https://github.com/rails/rails/blob/mast...